Using python PIL to turn a RGB image into a pure black and white image

Question

I\'m using the Python Imaging Library for some very simple image manipulation, however I\'m having trouble converting a greyscale image to a monochrome (black and white) ima

Answer 1

A PIL only solution for creating a bi-level (black and white) image with a custom threshold:

from PIL import Image
img = Image.open('mB96s.png')
thresh = 200
fn = lambda x : 255 if x > thresh else 0
r = img.convert('L').point(fn, mode='1')
r.save('foo.png')

With just

r = img.convert('1')
r.save('foo.png')

you get a dithered image.

From left to right the input image, the black and white conversion result and the dithered result:

You can click on the images to view the unscaled versions.